Carburizing and annealing furnace



Oct. 27, 1931. V DAUCH E AL 1,829,710

JARBURIZING AND ANNEALING FURNACE Filed Dec. 11, 1928 6 Sheets-Sheet v 1 INVENTOR Oct. 27, 1931. A. D. DAUCH ET AL CARBURIZING AND ANNEALING FURNACE Filed Dec. 11, 1928 6 Sheets-Sheet 2 INVENTOR Oct. 27, 1931.

.A. D. DAUCH ET AL CARBURIZING AND ANNEALING FURNACE Filed Dec. 11, 1928 6 Sheets-Sheet 3 INVENTOR MSW;

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' Oct. 27, 1931. A. D. DAUCH ET AL CARBURIZING AND ANNEALING FURNACE Filed Dec. 1,31, 1928 6 SheetsSheet 4 INVENTOR Oct. 27, 1931. DALJCH ET AL I 1,829,710

CARBURIZII JG AND ANNEALING FURNACE Filed Dec. 11, 1928 e Sheets-Sheet s INVENTOR M mwwe/ *6 7%... 6M @1644 Oct. 27, 1931. D UCH ET AL 1,829,710

CARBURIZING AND ANNE ALING FURNACE Filed Dec. 11 1928 6 Sheets-Shea? 6 I INVENTOR Patented Oct. 27, 1931 SYLVANIA, AN D JOSEPH SANDBERG; OF

PENNSYLVANIAfA oonroaar'ronor rnnnsvrvema CARBURIZING Al TD ANNEALING FURNACE Application filedDecember 11, 1928. Serial No. 325,372.

Thisainvention relates to carburi zing and annealing furnaces, and more particularly to multiple chamberxdoubler row types of counterfiow regenerative carburizing 'or annealing furnaces in which the material is conveyed through the furnace chamber by pusher mechanisms and in which alternate rows of material are moved in opposite directions through a preheating and cooling zone in which a heat exchange is effected by radiation andconvection as the cold materialin "its travel toward the heating zone passes adjacent a row of hot material travelling in the opposite direction.

It is among the objects of this invention to'-generally improve the" furnace structure to secu-reeconomy intheuse of heat and reduce the time for treating the articles. Another objectof' the-invention1s to reduce the heat losses'in furnaces of this-kind by providing doors on both the charge and discharge end to prevent through drafts. v Another object ofthe. invention is to provijde for automatic operation of the doors in conjunction with the operation of the pusher mechanism for; eeding thematerial through the furnace. l g Another object of theinvention'is to provide a furnace structure in which'the heat exchange between the heated andlcool articles passing out of and into the furnace is highly efficient. H Y 1 v V Another object of theinvention is to provide for independent regulation of temperature in: the several heating chambers and for controllinglthe temperature at different por tions of the individual chambers.

Another object of the invention is to provide a-furnace of. the above designated characterwhich shall operate on definite time and temperature cycles under complete automatic control. l j i Still another" object of the invention I is to provide for rapidly discharging thematerial from the furnacesto reduce the time at which the doors are open to a minimum; i

will become more apparent from consideration of the accompanying drawings in which characters designate like parts PATENT OFFICE RGE J. HAG-AN COMPANY, OF PITTSBURGH,

and in which Fig. 1 is a horizontal sectional view of a furnace structure embodying the principle of this invention; Fig. 2 is a diagrammatic view illustrating the distribution of heating elements employed in the heat chambers of the furnace; Fig. 3 is a crosssectional view of the furnace taken along the line III- H1 of Fig. 1; Fig. 4 is asimilar View taken along the line IVIV of Fig. 1; Fig. 5 is a sectional view of the charging end ,of the furnace taken along thelongitudinal center line thereof; Figure 6 is a similarview of the discharge end of-thefurnace;rFig 7 is a schematic View and wiring diagram of the door operating and pusher mechanismcontrol; and Fig. 8 is a wiring diagram of, the temperature control and regulating circuit, 7 no I Referring to Figures 1 to 6 inclusive of the drawings the structure therein illustrated comprises a furnace having side and end Walls 1 and 2 respectively divided into a plurality of chambers as follows A wall 8 extending through the longitudinal axis of of the preheating. and cooling chambers to.

efliciently exchange heat between heated material passing out of the furnaceand cold material entering the same. The bottom of the furnace is provided with piers 8 which are more clearly shown in Figures 5 and 6 of the drawings. these piers constituting spaced supports for a roller track 9 upon c whichthe articles to be treated orboxes in These andother 'ObjGCtS of the lnventlon which they are contained are conveyed LII ,shown'at 23"," the degreeof inclination being furnace chamber. 1 In the "furnace structure illustrated in Fig. 1, there are 4 rows'of piers Atthe'ends of therows the furnace is provided with charge and discharge 01) enings 13 and 14 respectively Which are co n-f f ,tliedra-vvin-gs, that the heatingfup zone of the chambers 41s adjacent the preheating fand' cooling chamber on the endof the furnace in vvhich the material is charged and the soaking zone is adjacent the preheating and cooling chamber located at the discharge end of'thefurnace.

"trolledsby doors 15-. 1 Th;ese doors, as shown n g s: an 3 a e Op r l motor drive comprising a'motor 16-, a sui-table reduction gear and a chain hoi'st17, the

latter passing over sheave. Wheels 18. ;and

guide pulleys 19 to obtain a directpull on the door 15.- The door operating motors is-schemati'callyshown at 20 in the drawings, this brake functioning .tofsjecure quick stopping'of'the in'otor when the door has" reachedlt he stoppositions in. its travel,j; v The material conveyed through the fur-o 'nac e bypusher mechanismjgenerally 'desig nate'd at 21,:Fig'. 'Zflvhich comprises a ram element- 22 thate'ngagesthe materi'al or containers and pushes' it on the roll-conveyor "fr'om'the c furnace," j I 11 For the purpose of se chamber; the roll conveyor is inclined as determined'hy the speed at which his desired to discharge the material. By ,sozini time for passing through thejoutlet passage drum furnaceand consequentlyfthe 'doo'r'is iop'ene d for minimum. time; thus reducing c the-loss of, heat. As shown fin-Fig." 6f, "the roll conveyor frame 2am be adjusted to various inclinations by: supporting it .on a

standardigd having-fastening means, such as jnotches or open1ngs'25 forrejceiving a pm 26 j projecting ,through'the frame, this pin beingv adaptedto be'placed in different open; 1ings 2 5= to vary ,the'iinclination of the con;

I y A ain referring-to Fig l of the dravvings', the individual-heatingchamber '4 is divided this zoneconstitutingthe heating i zone, and the other heating zone is rovided; with sidewall jelemenftsj52 andjno bottomlelement,

'ber'. 'In-a carburizingprocess it is desirable vingiq) fzone at a higher value than isjdesired 1' Q in th'epro'duct; the rated heat 'ahsorptionisi accelerated?- The rate of traV'el -of'the 'prod5 uctthrough'theheating up 'zoneandithe actual temperature uct enters the soakingzone Which is,

are provided with a vmagnetic brake which Figure'Tofhargefto the discharge end of the curing a rapi'd dis} Y charge of the material" from the ffu'rnac'e;

.c-lining the roll 'conveyorithe oxes 'cqfntainingthe treated matenals requ re 'ammimum into two zones which are adaptedto mam tain "different."temperatures, the one zone Whichfisrnear-the charging-endof thefur- 7 p heing-provided-withsidevvallilieatin'g g felementsi 30, Fig; 2'; and 'a botto'mjeleinent 31, v a

fliiS zon'e" being the soaking Zone of the chain- "toreduce the heating up timej'to' a minimum 7 andiloy setting'the temperature intheheat in this zone are so adjusted that the temperature of the product is substanti'ally'atthe desired value When the prodinbefore statedyheld at the, temperature de-. sired'intheproduct; .ia,

It will he noted with referenceto Fig. 1

To operatethe furnace ondefinite time and temperature cycles, it is necessary to provide automatic commune temperature regulation, the-latter beingeffected hy means of the equipment illustrated in Fig. '8 of the draw xings; which illustrates a plurality of thermocouples 83'Which are projected through the furnace inthe region oftheheatingelements in the heating ehamher; Temperature con trol is effected through the thermo couples by.

connecting the latterinthe power circuit of the resistorheating'elements through a series of-relays 34c which 'are controlled by an automatic temperature, controlling device indicated at 35, numerous types-of which are available forthispurpose; The heating element circuit iisconnectsby pu'sh'loutton staas heretions 37 and 38"which respectively disconnect the three element and the two element; zohesi For the purpose of controlling theiheatcycle of'the articles treated iin thefurnace, it is thearticle passes- 'thro'ugh the preheating and A timeclock is employed oforthis purpose 7 necessary-toregulate the time during which i and it functions-to:initiate"the-door operating mechanism fvvhich starts thetrain of door. The pusher mechanism for actuating the Work in moving it through the furnace'is 7 associated With; the door operating mechanism in such manner that their respective "events that is completed by the closing of the veyed through'the furnaceat predetermined time cycles or-iiitervals,imeans=mustbe pro- 7 "Vided fQr initiating the operation of the con veyin'g mechanism at predetermined intervals; such a means beingfillustrated as time "clock40 having-movable contacts 41 and a clock relay 42. Areversible' motor 161' drives the; door operating mechanism and the motor circuit" is 7 controlled Z by a plurality of limit switches 44, '45 and 46 that are actuated by movement ofthedoor v The door'foperatlng' mechan sm is electri- Cally; interlocked with there-harm mechaiiism, the latteizbeing'operated by a reversible motor 50" which is 'controlled by'a solenoid brake'51. The charger motor 50 is controlled by; limit switches 52 and 53'which are in cir cuit with the limit switches of the door mechg'anism and the motors 16 and 50 are respectively provided with motor startersand interlocks generally designated at 54 and 55 re- 'spectively. a V I Push'button switches 56 and 57, 58 and59, are provided for manually controlling the V circuitsiwhen desired;

' matic regulation of the temperature at'the predetermined values is elfected through the thermo-couples andthe control circuit.

The time clock 40 of Figure 7 is set to operate at given intervals and when the normally closed clock contacts 41 are opened for a shortinterval of time, the energizing circuit for the relay 42 is opened and this relay de-energizes. v 7

By thede-energization of the relay 42, a circuit is completed that extends from one side of the line'L-1, through normally closed contacts 44a of the limit switch 44, closed contacts of the pushbutton switch 56, closed contacts 42a of the de-energized relay [42, winding of the motor starter relay 60, to the -line'L 2. Relay'60 energizes and completes alocking circuit for itself, extending through the contacts of the interlock- 60a. The energizati'on of the relay 60 also completes the circuit'for the door motor 16, which'operates in a direction to raise the doors of the furnace. Y 7 1 Thedoors 15 are stopped in their full up 1 position by the operation of the limit switch 44 which-opens the above traced circuit of the motor relay 60. The relay 6O de-energizes andopens the circuit" of the motor 16, the

magnetic brake croperatin gito bring the motor and doors to rest. By the operation of the limit switch 44, a circuit is completed extending from L'1, normally closed contacts of the push button switch 57 contacts 44b of the limit switch 44, normally closed contacts 52a of the charger limit switch 52, winding of the relay 61, to the line L2. The

relay 61 energizes to establish the circuit of.

the charger motor 50,:which operates to push thecharger 21 in. I 7

When the charger reaches its fully inward position the limit switch 52 is operated to open the circuit of the relay 61, which deenergizes and opens the circuit of the charger motor 50. the magnetic break 51 operating to bring the motor and charger to rest." Another resu'lt of the operation of the limit switch 52, acircuit is completed extending from the line'L-l, closed contacts of the limit switch 46, closed contacts of the push button switch 59 and through the contacts limit switch '53, winding 'jc'har'ger movements may be 52b of the limit switch 52. From the contacts 526, the circuit divides, and extends through the winding ofthe relay 64 to line L2. Therelay 64 energizes andcompletes a locking circuit for itself, under control of the limit switch 46. The other circuit from the contacts 525 extends through the closed 62, which de-energizes and the door motor 16 is brought to rest as previously described. As another result of the operation of the limit switch 45, the contacts are closed to complete a circuit extending from L1, closed contacts of the push button switch 58, contacts 45?), the closed contacts 53a of the of the relay 63 to the line L2. The relay 63 energizes to complete the circuitfor the charger motor in the reverse direction to operate the charger outwardly. The charger is stopped in its full outward position by the operation of the limit switch 53.

The contacts 53a of the limit switch 53are opened to open the circuit of the relay 63 which de-energizes and the motor 50 is brought to rest as previously described. The operation of the limit switch 53'also closes .the'conta'cts 53?) which completes a circuit that extends from the line L1, contacts of the limit s'w'itch'46, contacts of the push button switch 59, contacts 64a of the relay 64 through the winding of this relay to line L 2. The above traced circuit is the previously mentioned locking circuit for this open thecircuit of the relays 64 and 62, thus completing the cycle of operations. When the clock contacts again open, the cycle of operations is the same as just described.

- The doors are stopped in their downward movement by the operation of the limit switchv 45 which should be adjusted to stop the doorsin a position which will just clear the charger head 22. V The time clock is set to; periodically initiate the cycle of events inaccordance with the duration of the treatment desired in the product.

; The location or the ends of the door and adjusted by adjusting the limit switches;

With the furnace structure hereinillus its;

L2. The relay 62 i- 

